Saturn_Europa
Senior Member
- Location
- Fishing Industry
- Occupation
- Electrician Limited License NC
I have a 15 hp, 3 phase, 480 v, 17 FLA, motor, running a multistage centrifugal pump. It was taken out of service today so our mechanics could replace the upper and lower bearings.
After re-installation it has been non-functional. The motor will come up to speed, run for a few minutes, pump water then trip the overloads. It has been blowing a single fuse, single phasing then dropping out on overloads. The fuses are LPJ-30SP , it was fully functional before the mechanics pulled it. It just had bad bearings.
The first time it did this it blew the B phase fuse. The second time it blew the C phase fuse.
I megged out the wire going to the motor from the motor starter and it was good. I megged the windings to ground and they are good. I ohmed out the windings and have roughly 0.9 ohms on each winding. There is no problem with the motor that I can detect.
The pump and motor spin freely by turning the fan on the top of the motor.
I am leaning to a phase to phase short caused by damage during bearing replacement. But I want to make sure I have thought about everything before I tell the guys they have to pull it again in 90 degree heat. Its not a fun job.
But I think I have checked everything, I can with the meters that I have. The wires are good going to the motor. Windings arent shorted or open. 480/277 V on the top of the motor starter before it I start the motor. Everything looks ok.
Any ideas?
After re-installation it has been non-functional. The motor will come up to speed, run for a few minutes, pump water then trip the overloads. It has been blowing a single fuse, single phasing then dropping out on overloads. The fuses are LPJ-30SP , it was fully functional before the mechanics pulled it. It just had bad bearings.
The first time it did this it blew the B phase fuse. The second time it blew the C phase fuse.
I megged out the wire going to the motor from the motor starter and it was good. I megged the windings to ground and they are good. I ohmed out the windings and have roughly 0.9 ohms on each winding. There is no problem with the motor that I can detect.
The pump and motor spin freely by turning the fan on the top of the motor.
I am leaning to a phase to phase short caused by damage during bearing replacement. But I want to make sure I have thought about everything before I tell the guys they have to pull it again in 90 degree heat. Its not a fun job.
But I think I have checked everything, I can with the meters that I have. The wires are good going to the motor. Windings arent shorted or open. 480/277 V on the top of the motor starter before it I start the motor. Everything looks ok.
Any ideas?
Last edited: